The use of molecular markers in apple breeding for disease resistance.

Molecular markers have become a useful tool simplifying and speeding up breeding work. They are also helpful in the genetic analysis of complex agronomic traits. The investigations concern the use of already available SCAR markers for molecular analysis of breeding materials. The markers are the apple powdery mildew resistance gene Pl2, originating from Malus zumi, and the apple scab resistance gene Vf, from M. floribunda 821. The clone U 211 was found to be highly resistant to mildew under field conditions and transmitted a high level of resistance to the majority of its progeny. The presence of the Vf gene conferring resistance to scab was confirmed by molecular analysis. As the molecular markers for the Pl2 gene are not present in the DNA of U 211, it is probable that the clone U 211 is a new source of mildew resistance.